It's not often one looks to the Guardian's environment pages for an incisive and thorough critique of green propagandising. But hats off – really – to Leo Hickman for this ruthless deconstruction of an erroneous claim made by David Attenborough on his latest BBC nature documentary that in the last twenty years Africa has warmed by 3.5 degrees C.

3.5 degrees C in two decades? That would indeed be a remarkable temperature rise in anybody's money. (Remember, since 1850 global mean temperatures have risen by about 0.8 degrees C – and we're supposed to find that worrying and significant). Which is why, you might have thought, the BBC would have spotted so obvious an error and removed it before the programme went out.

To his credit, this troubled Leo Hickman, too.

I'd never heard this arresting claim before. If that rate of temperature rise continued over, say, a century, then those parts of Africa would see a deathly rise of 17.5C?! Could that claim really be true?

Article continues below this advert:

So began his wild goose chase to track down the source of the BBC's factoid. As you'll see from his superb piece he never got a terribly satisfactory answer.

I was told that it came from a report published in 2006 by the "Working Group on Climate Change". The full title of the report was "Africa – Up in Smoke 2: The second report on Africa and global warming from the Working Group on Climate Change and Development" and it was "written and compiled" by Oxfam and the New Economics Foundation, with the support of a wide range of environmental and development NGOs such as Greenpeace, Friends of the Earth, WWF, Cafod and the Institute of Development Studies.

This, in turn, takes him to a report produced by Christian Aid; and thence to the Climatic Research Unit at the University of East Anglia – which has a stab at citing a "peer-reviewed" article in Nature, which doesn't support the claim made in the programme either.

What's rather touching about this is that Hickman is so surprised. Those of us who follow Donna Laframboise's research, for example, will have long been wearily familiar with the extent to which the IPCC's supposedly authoritative reports depend on "grey literature" – ie propaganda – produced by activists at organisations like Greenpeace, Friends of the Earth, Cafod, etc.

Hickman writes:

Personally, I find it bizarre – and frustrating – that an otherwise exemplary series, which took years to film, has been tainted – in my mind, at least – by such a sloppy piece of research. Why rely primarily on a seven-year-old report published an NGO? Why not just directly ask climatologists who would have the latest available data to hand? And how did the BBC's researchers even come across such an obscure fact? You get the sense they simply Googled "Africa temperature rise" and went for the first thing they found.

I agree. But it's so much nicer – and frankly more damning – when instead of my saying it comes from someone on the other side.

» How much "Man Made" CO2 Is In The Earth's Atmosphere?
I think ALL of the CO2 in the Earth's Atmosphere is from man.
I'm not sure how much "Man Made" CO2 is in the Earth's Atmosphere.
There is .04% CO2 in the Earth's Atmosphere and of that "Man" has added an extra 4% (1 part in 62,500)